Our research deals with the structure, assembly and function of microtubules, an organelle involved in chromosome segregation, cell motility, and the maintenance of cell shape. In the past year we have been studying a unique post-translational modification of tubulin (the protein building block of microtubules) which we think is an excellent candidate to regulate microtubule assembly or function. This involves the reversible enzymatic addition of a tyrosine residue to the C-terminus of the alpha-chain of tubulin. We are also studying the role of a calcium-specific ATPase as an auxilliary energy transducer or a component of the steering apparatus in Chlamydomonas flagella. A third project concerns the identification of a specific inhibition of dynein, the primary energy transducer in cilia and flagella.